The present invention relates to a silvicultural apparatus. More particularly, the present invention relates to a mobile silvicultural apparatus for use in a land of trees in order to carry out various silvicultural applications and also relates to the method for operating the same.
Known in the art is a silvicultural process which is referred to as xe2x80x9cpre-commercial thinningxe2x80x9d and which essentially consists in selectively thinning a land comprising mature trees and immature trees in order to keep only certain types of trees, mainly the immature trees, in order to carry out a commercially viable harvesting while allowing a proper regeneration of the land.
It is also known in the art that it is often difficult, dangerous, and expensive to perform pre-commercial thinning with motor-manual teams, especially when, for example, natural regeneration is dense and/or working grounds are not leveled. In such adverse circumstances, the risk of work accidents is high and manual operations are uneconomical. It would be therefore very useful to provide an apparatus and method for operating the same in order to carry out pre-commercial thinning in such adverse circumstances which would be safer, more efficient, and more cost-effective than what is possible with motor-manual teams.
Also known in the art are two main silvicultural processes for harvesting trees, namely the tree length harvesting process and the cut-to-length harvesting process.
The tree length harvesting process essentially consists in cutting trees with a mechanical tree feller, piling them on the cutting grounds, after which they are skid onto the side of the trails where they are then branched out.
The cut-to-length harvesting process essentially consists in cutting the tree stems with a multi-functional tree feller, branching out said stems and then cutting them to length on the cutting grounds. Afterwards, a transporter carries out the picking of the cut logs along the side of the trails.
These two main harvesting processes are designed so that equipment must often pass over the same tracks of a trail. In fact, by doing so, one tries to minimize the damages caused to the regeneration and to the soil by concentrating the passages at the same locations. Hence, with these harvesting processes, the surface protected is a function of the distance between the passages. Thus, it is often difficult to protect more than 75% of the land considering that the articulated booms which carry the harvester heads have a physical length limit and considering also that after several repeated passages along the same strips of land, both the soil and the regeneration along these strips are often destroyed by the machinery traveling thereover. This phenomenon is known as rutting. Furthermore, this resulting effect goes against one of the main principles in silviculture which consists in maintaining a good regeneration distribution coefficient. In fact, if one destroys 25% of the surface land after a harvest, the corresponding regeneration distribution coefficient is thus necessarily less than 75%, whereas it is often greater than 75% before the harvest even took place.
Therefore, in view of the above, it would be very useful to provide an apparatus and method for operating the same which when used for the above-mentioned harvesting processes, would enable to obtain a better regeneration distribution coefficient when compared to what is possible with some of the prior art.
Another silvicultural process known in the art is often referred to xe2x80x9cpre-commercial clearingxe2x80x9d which essentially consists in selectively clearing a land having brush and young trees in order to keep only certain types of trees, and removing the rest of the undesired brush and trees.
Selective clearing is a silvicultural process, which is generally done manually by workers equipped with portative brush clearing machines. The work involves selecting the stems of trees that are to be kept according to predetermined quantity and quality standards, and then cutting the rest of the brush with the portative brush clearing machine as workers walk on the field. It has been found that such a manual clearing technique requires an enormous amount of time and a large number of workers, especially if the surface to be cleared is large, thereby rendering this type of harvesting process cumbersome, time-consuming, and cost ineffective. Therefore, there is a need for an apparatus and method for operating the same which would enable to carry out improved selective clearing.
U.S. Pat. No. 4,355,670 granted on Oct. 26, 1982, to OHRBERG et al. discloses a vehicle having a clearing head located at the front of the vehicle for fragmenting woody material. The hydraulically adjustable clearing head includes a horizontally disposed cylindrical drum.
U.S. Pat. No. 4,236,554 granted on Dec. 2, 1980, to NICHOLSON, discloses a tractor having a front feller and chipper. The feller includes an elongated bladed rotary felling cutter head having its length extending transversely of the tractor between lower front portions. The chipper includes a chipping cutter head spaced upwards and rearward from the feller.
Also known to the Applicant are the following U.S. patents describing different harvesting devices: U.S. Pat. Nos. 3,754,603; 4,232,719; 4,390,134; 4,537,362; and 5,526,637.
None of the above-mentioned patents seem to disclose or even suggest a mobile silvicultural apparatus and method for operating the same which would overcome several of the above-mentioned problems associated with the prior art.
An object of the present invention is to provide a silvicultural apparatus and method associated thereto which would satisfy some of the above-mentioned needs, and would thus be an improvement over the harvesting devices and methods known in the art.
In accordance with the present invention, the above object is achieved by a mobile silvicultural apparatus for use in a land of trees, the apparatus comprising:
a steerable wheeled support frame comprising a horizontally extending ground-clearing section, and first and second opposite vertical side sections, the ground-clearing and side sections defining a tunnel-shaped passage through which trees of a certain type are allowed to pass as the support frame travels thereover;
manipulating means mounted to the support frame for selectively manipulating trees of the land;
motor means for imparting motion to the support frame; and
control means for controlling the steerable support frame, the motor means, and the manipulating means.
According to a first preferred embodiment of the present invention, there is provided a land clearing tractor for selectively clearing a land of brush and trees, the tractor comprising:
a traction unit for moving the tractor along a direction of travel;
a supporting frame connected to the traction unit, the frame having first and second sides, and a raised section between the first and second sides;
a first shredder head operatively connected to the first side of the frame and oriented parallel to the direction of travel, the first shredder head being movable between elevated and lowered positions for clearing brush and trees in a first band; and
a second shredder head operatively connected to the second side of the frame, the second shredder head being parallel to the first shredder head and spaced apart therefrom, the second shredder head being movable between elevated and lowered positions for clearing brush and trees in a second band spaced apart from the first band and thereby leaving between the first and second bands a residual band of brush and trees.
As can be appreciated, the land clearing tractor according to the first preferred embodiment of the present invention cuts brush and trees in a pair of spaced apart bands so that brush and trees between the cut bands can be later selectively cut.
According to another aspect of the first preferred embodiment of the present invention, there is also provided a land clearing tractor for selectively clearing a land of brush and trees, the tractor comprising:
a traction unit for moving the tractor along a direction of travel;
a frame having an inverted U-shaped cross-section with first and second sides, and a raised section between the first and second sides positioned between 0.5 and 1.5 meters from ground;
a first shredder head operatively connected to the first side of the frame through a first actuating lever arm, the first shredder head being oriented parallel to the direction of travel and being movable between elevated and lowered positions for clearing brush and trees in a first band; and
a second shredder head operatively connected to the second side of the frame through a second actuating lever arm, the second shredder head being parallel to the first shredder head and spaced apart therefrom, the second shredder head being movable between elevated and lowered positions for clearing brush and trees in a second band spaced apart from the first band and thereby leaving between the first and second bands a residual band of brush and trees.
According to yet another aspect of the first preferred embodiment of the present invention, there is also provided a process for selectively clearing brush and trees of a land, comprising the steps of:
clearing simultaneously first and second parallel and spaced apart bands of brush and trees with a land clearing tractor; and
manually and selectively cutting brush and trees in a residual band between the two parallel and spaced apart bands.
According to a second preferred embodiment of the present invention, there is provided a mobile silvicultural apparatus for use in a land of trees comprising mature trees and immature trees, the apparatus comprising:
a steerable wheeled support frame comprising a horizontally extending ground-clearing section, and first and second opposite vertical side sections, the ground-clearing and side sections defining a tunnel-shaped passage through which the immature trees are allowed to pass as the support frame travels thereover;
an articulated boom mounted to the support frame for selectively manipulating the mature trees;
motor means for imparting motion to the support frame; and
control means for controlling the steerable support frame, the motor means, and the articulated boom.
Preferably, the tunnel-shaped passage has a smooth configuration in order to minimize damages to the immature trees passing through the tunnel-shaped passage as the ground clearing section of the support frame travels over said immature trees.
Preferably also, the articulated boom comprises a harvester head selected from the group consisting of a multi-functional tree feller and a grapple for grappling a tree.
Preferably also, the steerable wheel support frame comprises front and rear units and a universal joint coupling the front unit to the rear unit.
Preferably also, front and rear wheeled assemblies are mounted respectively to the front and rear units of the support frame. These front and rear wheeled assemblies preferably comprise hydrostatic motor-wheels.
According to another aspect of the second preferred embodiment of the present invention, there is also provided a silvicultural method for harvesting mature trees in the land of trees comprising mature trees and immature trees, the method comprising the steps of:
a) providing the above-mentioned apparatus;
b) driving the apparatus of step a) along a first strip of the land;
c) stopping the apparatus at different locations along said strip of land; and
d) felling and harvesting mature trees located around said different locations.
Preferably, the silvicultural method comprises the additional steps of:
e) providing a mobile silvicultural apparatus according to a transporting embodiment of the invention;
f) driving the apparatus of step e) along said strip of land; and
g) picking up at each of said different locations the harvested mature trees and transporting the same outside the land.
Preferably also, the silvicultural method comprises the step of:
h) sequentially repeating steps a) to g) along additional strips of land substantially parallel to said first strip of land until a desired portion of the land is harvested.
Preferably also, the silvicultural method comprises, prior to performing a first sequence of steps a) to g), a step of determining a distance between each said strips of land, said distance being determined such that a minimum amount of said strips is required to harvest the desired portion of the land.